Suction belt separator for flat items

ABSTRACT

A suction belt separator in which the passage between a suction opening for removing items from a stack and the vacuum source extends across the conveying path followed by separated items so that an item intersecting the passage blocks it and interrupts the suction at the suction opening, the suction opening also being in permanent communication with the atmosphere through a small throttle opening.

United States Patent Burkhardt Mar. 14, 1972 [54] SUCTION BELT SEPARATORFOR [56] References Cited FLAT ITEMS UNITED STATES PATENTS [72]Burkhardt Re'chenau Germany 3,279,786 10/1966 Fliegner et a1 ..27|/12[73] Assignee: Licentia Patent-Verwaltungs-G.m.b.ll., 3,131,929 5/1964Rehm ....271/26 Frankfurt am Main, Gennany 3,258,262 6/1966 Rehm..271/32 [22] Wed: Feb- 2 1970 2,970,834 2/1961 Martin et al. ..271/26[21] App1.No.: 7,965 Primary Examiner.loseph Wegbreit Att0rneySpencer &Kaye [30] Foreign Application Priority Data 57 ABSTRACT Jan. 31, 1969Germany ..P 19 04 705.3 A suction b lt ator in which the passage betwee3 tion opening for removing items from a stack and the vacuum US. Cl...271/26 R, 271/12 rce extends across the conveying path followed byseparated items so that an item intersecting the passage blocks it andinterrupts the suction at the suction opening, the suction opening alsobeing in permanent communication with the atmosphere through a smallthrottle opening.

4 Claims, 2 Drawing Figures VACUUM SOURCE Patented March 14, 1972 VACUUMSOURCE Gisbmt Bmkha Tdt SUCTION BELT SEPARATOR FOR FLAT ITEMS BACKGROUNDOF THE INVENTION The present invention relates to a suction beltseparator for flat items, particularly those having different lengths,such as letters for example.

The invention is particularly directed to the type of separators inwhich the suction chamber disposed opposite the stack is incommunication with the vacuum source through a control channelextending, at a distance from the suction point which is less than thelength of the shortest item, across the conveying channel and which iscontrolled directly by the already separated item then passing throughthe separator.

The regulation of the suction applied to the stack in dependence on theposition of the trailing edge of the preceding item can produce theresult that the items will not be conveyed with their front edges spacedat constant intervals but with gaps of constant length therebetween,which may be desirable, for example, at different points within anautomatic mail distribution system.

A suction belt separator having these properties and in which thesuction chamber opposite the stack is also controlled by directpneumatic means is disclosed in German Pat. No. l,l77, l 74. Thisseparator is so constructed that the rotating perforated belt is broughtpast two suction chambers, one behind the other in the conveyingdirection, with the second chamber, seen in the conveying direction,being connected with a suction air source whereas the first chamber isconnected with a third suction chamber disposed on the other side of theconveying path from the second chamber and cooperating with its ownrotating conveying member. This third suction chamber receives itssuction from the first suction chamber across the suction channel.

To assure that the spaces between consecutive items are indeedsubstantially constant in such an arrangement, it is necessary for thepressure in the suction chamber to be quickly restored. Because after,for example, an item having the shortest possible length has covered thecontrol channel, its trailing edge must not release the suction openingsof the suction chamber opposite the stack until the vacuum previouslypresent in this chamber has been dissipated. Otherwise there would occuran overlapping removal. For a given apparatus size, the length of theshortest item that can be handled is thus directly dependent on thereplenishment time of the volume of air to be controlled. In the knownarrangement constructed with three suction chambers the volume to becontrolled includes the interior of two suction chambers-Le, the chamberopposite the stack and the third suction chamber-as well as the movablehose connecting the chambers which, for structural reasons, has arelatively large volume.

SUMMARY OF THE INVENTION A primary object of the present invention is toeliminate the shortcomings of these known devices.

A further object of the invention is to increase the item-handling rateof such devices.

Another object of the invention is to permit a device of given size tohandle shorter items than was heretofore possible.

Yet another object of the invention is to simplify the structure of suchdevices.

It is a specific object of the present invention to construct a suctionbelt separator of the type mentioned in the introductory paragraph insuch a manner that a substantially smaller air volume must becontrolled.

These results are achieved according to the invention by forming thecontrol channel between control openings disposed in the suction chamberitself and the suction openings of a second suction chamber which isdisposed opposite the first suction chamber together with a rotatingperforated belt, the second chamber and belt being mounted in a knownmanner to be resiliently urged toward the first chamber, the vacuumsource being connected directly to the second suction chamber and thefirst suction chamber being in communication with the atmosphere througha throttle opening.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a plan view, partly in crosssection, of a suction belt separator according to the invention forletters.

FIG. 2 is an elevational view of an element of the arrangement of FIG.1.

DESCRIPTION OF THE PREFERRED EMBODIMENTS The separator illustrated inFIG. 1 includes a first suction chamber 2 disposed opposite the stack 1of letters. A suction belt 5 is brought past chamber 2 and over a driveroller 3 and a guide roller 4 and is provided with perforations alongits length. The abutment wall for the stack is indicated at 6. Astripper 7, which may be a known suction stripper, is shownschematically behind the initial suction region and is disposed on theside of the conveying path opposite the suction belt 5.

Suction chamber 2 is in communication with the atmosphere through athrottle opening 8 having a small cross section. The chamber wall 2'facing the suction belt 5 is provided with suction openings 9 in theinitial suction region, which openings cooperate in a known manner withthe suction belt. Control openings 10 are provided in wall 2 at alocation such that the total length D of the path covered by openings 9and 10 and the distance between them is not greater than, and preferablyless than, the length of the shortest item to be separated, and in sucha manner they are also disposed in the paths of the openings of suctionbelt 5. The effective width of the suction region defined by openings 10should be no greater than the width of the narrowest item to beseparated.

As shown in FIG. 2, narrow suction slits 9 are formed in wall 2 in linewith the paths of the belt openings and extending between the suctionopenings 9 and control openings 10, the slits being provided to effect apositive transport of the items.

A second suction chamber 11 is disposed opposite the control openings 10of suction chamber 2 and is provided with suction openings 11' inregistry with the control openings 10. An auxiliary belt 14 passes infront of this second suction chamber 11 and is guided around rollers 12and 13. This belt is also provided with openings which extend along itsedges in line with the openings in suction belt 5 and thus in line withthe control openings 10 and suction openings 11. A separate drive may beprovided for auxiliary belt 14, but is not necessary since belt 14 willbe driven by contact with belt 5. Suction chamber 11 is connected to avacuum source 20 through a hose l5.

Suction chamber 11 and the shafts of rollers 12 and 13 are fastened to asupporting bar 16 which is mounted on an arm 17 to be freely movableabout an axis perpendicular to its length. Arm 17 is itself pivotalabout an axis 18 and is urged in a counterclockwise direction by atension spring 19. Thus, the auxiliary belt 14 is always maintained incontact with suction belt 5 or with the item carried along therewith.

The above-described suction belt separator operates as follows:

Let it be assumed that no item is in the conveying path when the suctionbelt 5 is put into operation. The control channel formed between suctionopenings 11 and control openings 10 is thus open so that a vacuum isdeveloped in suction chamber 2. Thus, the first item in the stack issucked onto the belt 5 through the suction openings 9 and is removedfrom the stack with the aid of the narrow suction slits 9'. As soon asthe control openings 10 have been covered by the item passing through,the connection between suction chamber 2 and the vacuum source isinterrupted and the suction in chamber 2 is dissipated by the passage ofair through throttle opening 8 so that a suction effect no longerexists. Since the item, however, is now pressed between belts 5 and 14,it is further transported, simply by friction, between belts 5 and 14.After the trailing edge of the item passes openings 10, those openingsare free again so that a new vacuum is formed in suction chamber 2 andthe next item is sucked onto belt 5 and removed from the stack.

The size of throttle opening 8 can be selected in a straightforwardmanner as a function of the volume of chamber 2 and the time in whichthe vacuum in the chamber is to be dissipated.

It will be understood that the above description of the presentinvention is susceptible to various modifications, changes andadaptations and the same are intended to be comprehended within themeaning and range of equivalents of the appended claims.

lclaim:

1. A suction belt separator for separating flat items from a stack andfor moving them along a conveying path, comprising, in combination:

means defining a region in which the stack is placed;

a first suction chamber disposed opposite the stack region, said chamberhaving a suction opening communicating with the stack region, a controlopening spaced along the conveying path from said suction opening by adistance not greater than the length of the shortest item to beconveyed, and a throttle opening communicating with the atmosphere;

a second suction chamber disposed on the opposite side of the conveyingpath from said first chamber, said second chamber being urgedresiliently toward said first chamber and having a suction openingdisposed opposite said control opening and forming therewith a controlchannel extending across the conveying path; a vacuum source connectedto said second chamber; and a moving belt moving along the conveyingpath and across said suction and control openings at the same side ofthe conveying path as said first chamber, said belt having a series ofsuction perforations in line with said openings;

whereby: said suction opening of said first chamber is in communicationwith said vacuum source only through said control channel; an item canbe taken from the stack and conveyed by said belt only when a suctionexists at said suction opening of said first chamber; and the suction atsaid suction opening of said first chamber is interrupted when an itemintersects said channel so as to block communication between saidcontrol opening and said second chamber suction opening.

2. An arrangement as defined in claim 1 wherein said first chamberfurther has narrow suction slits extending between said suction openingof said first chamber and said control opening and communicating withsaid belt.

3. An arrangement as defined in claim 1 wherein said first chamber has aplurality of suction openings extending across the width of theconveying path and a plurality of control openings extending across thewidth of the conveying path.

4. An arrangement as defined in claim 1 further comprising a second beltmoving across said suction opening of said second chamber on theopposite side of the path from said first defined belt.

1. A suction belt separator for separating flat items from a stack andfor moving them along a conveying path, comprising, in combination:means defining a region in which the stack is placed; a first suctionchamber disposed opposite the stack region, said chamber having asuction opening communicating with the stack region, a control openingspaced along the conveying path from said suction opening by a distancenot greater than the length of the shortest item to be conveyed, and athrottle opening communicating with the atmosphere; a second suctionchamber disposed on the opposite side of the conveying path from saidfirst chamber, said second chamber being urged resiliently toward saidfirst chamber and having a suction opening disposed opposite saidcontrol opening and forming therewith a control channel extending acrossthe conveying path; a vacuum source connected to said second chamber;and a moving belt moving along the conveying path and across saidsuction and control openings at the same side of the conveying path assaid first chamber, said belt having a series of suction perforations inline with said openings; whereby: said suction opening of said firstchamber is in communication with said vacuum source only through saidcontrol channel; an item can be taken from the stack and conveyed bysaid belt only when a suction exists at said suction opening of saidfirst chamber; and the suction at said suction opening of said firstchamber is interrupted when an item intersects said channel so as toblock communication between said control opening and said second chambersuction opening.
 2. An arrangement as defined in claim 1 wherein saidfirst chamber further has narrow suction slits extending between saidsuction opening of said first chamber and said control opening andcommunicating with said belt.
 3. An arrangement as defined in claim 1wherein said first chamber has a plurality of suction openings extendingacross the width of the conveying path and a plurality of controlopenings extending across the width of the conveying path.
 4. Anarrangement as defined in claim 1 further comprising a second beltmoving across said suction opening of said second chamber on theopposite side of the path from said first defined belt.